A semiconductor device used as a central processing unit (CPU) or the like is electrically connected to and fixed on a board in a semiconductor package. The temperature of the semiconductor device becomes high at the time of its operation. Therefore, the semiconductor device may be damaged unless its temperature is forcibly reduced. Accordingly, a heat spreader or a radiator fin (or a heat pipe) is attached on the semiconductor device to ensure a path for effectively radiating heat generated by the semiconductor device to its outside. Attempts have been made at smooth heat conduction by interposing a thermal interface material (TIM) between the semiconductor device and the heat spreader or the like so that the thermal interface material follows their respective uneven surfaces to reduce thermal contact resistance.
FIG. 1 is a cross-sectional view of a conventional semiconductor package including a thermal interface material. In the semiconductor package, heat generated by a semiconductor device 200 mounted on a board 100 is transferred to a heat spreader 400 via a thermal interface material 300a provided on the semiconductor device 200. Further, the heat transferred to the heat spreader 400 is transferred to a radiator fin 500 via a thermal interface material 300b provided on the heat spreader 400.
Thus, the thermal interface materials 300a and 300b are used as means for thermally connecting the semiconductor device 200 and the heat spreader 400 and thermally connecting the heat spreader 400 and the radiator fin 500.
Reference may be made to Japanese Laid-Open Patent Application No. 57-039364 for related art.